remove method call receiver special casing in unused_async lint

Author: y21

clippy_lints/src/unused_async.rs

@@ -2,7 +2,7 @@ use clippy_utils::diagnostics::span_lint_hir_and_then;
 use clippy_utils::is_def_id_trait_method;
 use rustc_hir::def::DefKind;
 use rustc_hir::intravisit::{FnKind,Visitor, walk_expr, walk_fn};
-use rustc_hir::{Body,Expr,ExprKind,FnDecl,Node,YieldSource};
+use rustc_hir::{Body,Expr,ExprKind,FnDecl,HirId,Node,YieldSource};
 use rustc_lint::{LateContext,LateLintPass};
 use rustc_middle::hir::nested_filter;
 use rustc_session::impl_lint_pass;
@@ -137,17 +137,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedAsync {
 }
 }
 
-fncheck_path(&mutself,cx:&LateContext<'tcx>,path:&rustc_hir::Path<'tcx>,hir_id: rustc_hir::HirId){
-fnis_node_func_call(node:Node<'_>,expected_receiver:Span) -> bool{
-matches!(
- node,
-Node::Expr(Expr{
- kind:ExprKind::Call(Expr{ span, .. }, _) | ExprKind::MethodCall(_,Expr{ span, .. }, ..),
- ..
-})if*span == expected_receiver
-)
-}
-
+fncheck_path(&mutself,cx:&LateContext<'tcx>,path:&rustc_hir::Path<'tcx>,hir_id:HirId){
 // Find paths to local async functions that aren't immediately called.
 // E.g. `async fn f() {}; let x = f;`
 // Depending on how `x` is used, f's asyncness might be required despite not having any `await`
@@ -156,7 +146,14 @@ impl<'tcx> LateLintPass<'tcx> for UnusedAsync {
  && letSome(local_def_id) = def_id.as_local()
  && cx.tcx.def_kind(def_id) == DefKind::Fn
  && cx.tcx.asyncness(def_id).is_async()
- && !is_node_func_call(cx.tcx.parent_hir_node(hir_id), path.span)
+ && let parent = cx.tcx.parent_hir_node(hir_id)
+ && !matches!(
+ parent,
+Node::Expr(Expr{
+ kind:ExprKind::Call(Expr{ span, .. }, _),
+ ..
+})if*span == path.span
+)
 {
 self.async_fns_as_value.insert(local_def_id);
 }

tests/ui/unused_async.rs

@@ -55,6 +55,22 @@ mod issue9695 {
 }
 }
 
+mod issue13466 {
+use std::future::Future;
+
+structWrap<F>(F);
+impl<F>From<F>forWrap<F>{
+fnfrom(f:F) -> Self{
+Self(f)
+}
+}
+fntakes_fut<F:Fn() -> Fut,Fut:Future>(_:Wrap<F>){}
+asyncfnunused_async(){}
+fnfp(){
+takes_fut(unused_async.into());
+}
+}
+
 asyncfnfoo() -> i32{
 //~^ ERROR: unused `async` for function with no await statements
 4

tests/ui/unused_async.stderr

@@ -27,7 +27,7 @@ LL | async fn f3() {}
  = help: consider removing the `async` from this function
 
 error: unused `async` for function with no await statements
- --> tests/ui/unused_async.rs:58:1
+ --> tests/ui/unused_async.rs:74:1
  |
 LL | / async fn foo() -> i32 {
 LL | |
@@ -38,7 +38,7 @@ LL | | }
  = help: consider removing the `async` from this function
 
 error: unused `async` for function with no await statements
- --> tests/ui/unused_async.rs:70:5
+ --> tests/ui/unused_async.rs:86:5
  |
 LL | / async fn unused(&self) -> i32 {
 LL | |